1. Field of the Invention
This invention relates to heating method and apparatus of the type which produces heat by burning gases for the purpose of soldering or other processes, and more particularly to improved method and apparatus which permit a controlled amount of suitable liquefied gases from a gas container to be electrically ignited and burned by the oxidation reaction of catalysts in a combustion chamber to turn to flameless thermal energy which conducts through a heat conductor whose tip is thereby heated to high temperatures.
2. Description of the Prior Art
For soldering connections of electrical wires, cutting a sheet of synthetic resin and bonding two parts of synthetic resin material together, heat sources are required and heat is usually obtained from an electrical heating source. When the above soldering, cutting and other works are performed in the field, there arises at all times the need to secure any type of external electrical power sources and, for connection to any power source, a power line cord is required which prevents progress of the work, reducing the operational efficiency. Particularly, when the work is done outdoors, greater difficulties are encountered in securing the power supply and the work is made practically impossible.
In order to carry out the soldering work in places where no power supply is available, a non-electrically operated heating apparatus such as a torch lamp or blow lamp is used instead of the above electrically operated heating apparatus. When the torch lamp is used, a separate hot element or rod is required to which heat is applied by the heating apparatus for carrying out the soldering work. Alternatively, the torch lamp is equipped with a copper element at the spot from which flames are developed so that the copper element is heated under the flames. In the case of the separate hot element, the soldering work has limitations because of the limited heating capability of the hot element. In other words, it is practically impossible to apply heat to the element during the process of the soldering work while the element must be heated to a soldering temperature each time it becomes cool or less hot, thus involving discontinuity of the soldering work which results in a decreased work rate or lowered efficiency. To avoid the above, the rod element may be enlarged to a size which can contain a sufficient amount of heat for a longer lasting period, but the heat storage inherently does not last as long as it should. Then, in order to secure the capability of storing heat or to make it last much longer, it may be necessary to further increase the size at the tip of the hot element, but this may adversely affect the soldering work, making it extremely difficult or almost impossible to join relatively small connections of electrical wires or components, particularly those on a printed wiring board. If the tip is then made smaller, it cannot retain a sufficient amount of heat to keep the tip hot for a longer time. As readily understood from the foregoing, the separate hot element has a number of limitations in size and shape as well as problems in handling, resulting in limited applications or uses.
The copper element, which forms a part of the torch lamp, has also problems and disadvantages since in this case it is difficult to adjust the supplied heat to desired temperatures and it is impossible to eliminate the flames emitted from the torch lamp. When the soldering work involves joining very small parts such as on a printed wiring board, the flames may cover the parts to be joined so much that it becomes difficult to see the work. If the flames are strong and expand widely, they may cover the neighboring parts or combustible material parts which should not be heated, causing those parts to burn out accidentally. The flames of the burning parts may eventually expand over to other parts, resulting in a whole disaster, and this is not desirable from a safety aspect in addition to the technical operational aspects mentioned earlier. A different form of soldering tool heretofore known contains a secondary cell such as a nickel-cadmium cell, and is known as a cordless soldering device. This tool has a limited heating capacity so that it cannot be used continuously for a long period of time. A further disadvantage of the tool is that it takes longer to recharge the cell, and if the cell should completely be exhausted by carelessness to an extent that it can no longer discharge at all and the tool must be replaced. Thus, the cordless soldering tool has disadvantages in both economical and operational aspects. As an alternative form of soldering elements which are heated by external heating sources, such as typical torch lamps or blow lamps, there is known a heating apparatus of the type in which a gas is burned in a combustion chamber to be converted to thermal energy which conducts through a heat conductor to its tip end. This heating apparatus poses problems since it is difficult to deliver a small quantity of gas at a uniform and constant rate into a relatively small combustion chamber, and it is also impossible to prevent flames from expanding or extending out of the apparatus.